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Hearing Conservation Theresa Y. Schulz, PhD. Lt. Col. USAF (ret.) Topics Noise And Acoustics Noise Reduction Reducing Costs for Hearing Loss Motivating Workers Noise + Acoustics Noise-Induced Hearing Loss Causes no pain Causes no visible trauma Leaves no visible scars Is unnoticeable in its earliest stages Accumulates with each overexposure Takes years to notice a change Is Permanent + 100% Preventable Noise + Acoustics Noise-induced hearing loss is the most common permanent and preventable occupational injury in the world. World Health Organization Noise + Acoustics Worker’s Compensation In many countries, excessive noise is the biggest compensable occupational hazard. Cost of NIHL to developed countries ranges from 0.2 to 2% of its GDP. NIHL is on the rise globally. (Source: WHO) Noise + Acoustics United States Statistics Most common occupational injury in the United States. 22 million US workers are exposed to hazardous noise at work on a daily basis. Approx. 8 million Americans suffer from NIHL. (Source: NIOSH, 2009) Noise + Acoustics Non-Occupational Occupational Noise + Acoustics Noise Measurement Devices SOUND LEVEL METER PERSONAL DOSIMETER IN-EAR DOSIMETER Sound is measured immediately in a specific area Sound “averaged” throughout day for sample employee/job Collects personal noise dose – the only real measure of risk NOISE+AND Noise Acoustics ACOUSTICS - Hierarchy ~ Hierarchy of Controls of Controls ENGINEERING CONTROLS • Buy Quiet • Vibration Pads • Enclosures ADMINISTRATIVE CONTROLS • Rotate Workers • Barriers • Extended Breaks • Isolation •2nd/3rd Shift PERSONAL PROTECTIVE EQUIPMENT NOISE+AND Noise Acoustics ACOUSTICS ~ Hierarchy of Controls Ototoxic Chemicals • • • • Ototoxic by themselves Synergistic effect with noise Large differences in sensitivity Recommend: increased frequency of audiometric testing Confirmed Ototoxics Ethyl Benzene Lead and inorganic compounds (as Pb) Styrene Toluene Trichloroethylene Synergistic Ototoxics NOISE • Carbon Monoxide Possible Carbon disulfide • Hydrogen Cyanide n-Hexane Xylene Noise Reduction Rating (NRR) Hearing Protection Selection Hearing Protection Selection Factors Comfort Noise Reduction Size Communication Job Requirements Hygiene Use with Other PPE • Proper Select The Selecting Every Keep Consider right workers ear HPDs care hearing job HPDs canal and thathas with can protector suitable its connected requirements maintenance work own with shape attenuation should other to their can in and PPE HPD feel comfortable for size environment selection extend without noise life compromise environment and ofmay • performance One protector Avoid Ensure Uniform Detectable Cap-mounted overprotection proper attenuation earplugs fitHPDs with • earmuffs notmarginal in variety allows for Examine process satisfy speech/signals of for and earplug all noise industries hard workers clean environments sizes to all be multiple-use hear and shapes more • hats Offer Hi-visibility a variety earmuffs of naturally daily • earplugs earplugs Consider Sized for Multiple-position dark/high multiple-use or banded earmuffs traffic • earmuffs to meetand earplugs Sound areas Clean amplification varying forreplace full-brim worker intermittent earmuffs ear cushions hats needs for noise workers on and or • hard Low-pressure Dielectric HPDs foam for preferences electronic with hearing every earmuffs 4-6 for • earmuffs earplugs electrical Ultraslim for neckband smaller impact impairment months noise. ear canals environments earmuffs with welding shields Noise Reduction Rating Noise Level = 100 dB Noise Reduction Rating = 30 dB How much noise is reaching the ear of the worker ? That is completely unknown … (55 – 104 dB) 0 dB 0 dB 33 dB EAR #1 EAR #2 EAR #3 How much protection? Fitting Tips Good Fit vs Bad Fit 90 Attenuation in dB 80 70 60 50 40 30 20 10 0 -10 Max Good Fit NRR = 33dB Max Poor Fit NRR = 0dB 8000 6300 4000 3150 2000 1000 500 250 125 Frequency in Hz Noise Reduction Rating Noise Reduction Rating • A laboratory estimate of the amount of attenuation achievable by 98% of users when properly fit • A population-based rating ― some users will get more attenuation, some will get less The NRR is only a population estimate, not a predictor of individual attenuation. Noise Reduction Rating – Determining an NRR • 10 human subjects tested in a reverberant room • Tested with ears open/occluded at nine frequencies • Each subject tested 3x • NRR calculated to be population average A test subject in the Howard Leight Acoustical Lab, San Diego, CA, accredited by the National Voluntary Laboratory Accreditation Program (NVLAP) Noise Reduction Rating – Determining an NRR NRR NRR Number of test subjects 5 4 3 2 1 14 18 20 22 24 26 28 30 32 19 23 25 27 Attenuation Noise Reduction Rating Attenuation in dB Real-World Attenuation ≠ NRR 192 users of a flanged reusable earplug ~ 27 NRR 50 NRR = 27 Multiple-Use Earplug 40 30 20 10 0 -10 From Kevin Michael, PhD and Cindy Bloyer “Hearing Protector Attenuation Measurement on the End-User” Retraining and refitting resulted in an average 14 dB improvement for this group Noise Reduction Rating De-Rating Methods OSHA NIOSH CSA NRR ÷ 2 Earmuffs NRR – 25% Class A up to 100 Formable Earplugs NRR – 50% B up to 95 (feasibility of engineering controls) Fit Test All Other Earplugs NRR – 70% C up to 90 Noise Reduction Rating Noise Reduction Rating • The EPA recently made an announcement about a proposed change to the Noise Reduction Rating [NRR] • This is the first change in hearing protector regulation in nearly 30 years Noise Reduction Rating Determining New NRR • 20 human subjects tested in a simulated industrial room • Subject trained then fits their own earplugs • Tested with ears open / occluded at 9 frequencies • Each subject tested 2x • NRR calculated to be population average New NRR (NRsa) 80% achieved > 20 dB 20% achieved > 26 dB Number of test subjects 5 4 3 2 1 11 14 18 20 22 24 26 28 30 19 23 25 27 Attenuation 33 Noise Reduction Rating Current NRR Label 80th % 20th % Minimallytrained Proficient Users Mock-up of New Label Noise Reduction Rating How to Apply the New Label Two-number range displays the estimated protection achievable by minimally-trained users [80%] versus proficient users [20%]. 80% 20% A wider range indicates greater variability in the fit of that HPD. Smaller ranges indicate more consistency of fit. For example, earmuffs will usually have a tighter fitting range than earplugs, and may have a smaller NRR range. Noise Reduction Rating Factors in Achieving the NRR 1.FIT 2. WEAR TIME 30 A worker who selects an earplug with an NRR of 30 but then removes that HPD for just … effectively reduced his 8-hour NRR to just … dB 5 min 10 min 15 min 30 min 26 dB 24 dB 22 dB 18 dB In noise exposures, small intervals of no protection quickly void large intervals of adequate protection. Noise Reduction Rating What Can I Do Now? Although the new labeling regulation takes effect whenever the final rule is published by the EPA, there are a number of actions you can take now to prepare your Hearing Conservation Program for the change. • Evaluate Noise Spectra to determine if spectral balance corrections will be necessary • Update HC Training Program on proper fit of hearing protectors. Hold a “Toolbox Training” and hold a refresher fit training session. Noise Reduction Rating What Can I Do Now? • Evaluate Current HPD Selection to determine whether they are appropriate for your noise environment. Use the Howard Leight Hearing Protector Selector for recommendations. • Upgrade to One-on-One Training research studies confirm that one-on-one training is superior to group training Noise Reduction Rating Earplug Fit Testing Provides an accurate, real-world picture of your employees’ hearing protector effectiveness. Identify if your employees are: • Receiving optimal protection • Require additional training • Need to try a different earplug style Noise Reduction Rating Earplug Fit Testing As a problem solver: • Derating Schemes • One-on-One Training • HPD Selection • NRR Change Noise Reduction Rating In-Ear Dosimetry As a Problem Solver • Continuously monitors in noise level at the workers ear • The only true measure of the hazard! Reducing Costs of Hearing Loss Reducing Costs of Hearing Loss Sample HL Compensation* One Ear (Max) $37.2k $38.7 Both Ears Comments (Max) (80 wks) (165 wks) TN $38.6k $77.2k + aids DOL -LSA 52 wks 200 wks + aids Jurisdiction NC SC $80k $80k + aids *NMER *NMER= No minimum exposure required *Source: AIHA Noise Manual Reducing Costs of Hearing Loss Indicators for Hearing Loss: • • • • • • • Standard Threshold Shift Temporary Threshold Shift Recordable Hearing Loss Dosimetry In-ear Dosimetry Personal Attenuation Level (PAR) Hearing Loss Compensation Reducing Costs of Hearing Loss Lagging Indicators vs. Leading Indicators Reducing Costs of Hearing Loss Indicators for Hearing Loss: • • • • • • • Standard Threshold Shift Temporary Threshold Shift Recordable Hearing Loss Dosimetry In-ear Dosimetry Personal Attenuation Level (PAR) Hearing Loss Compensation Reducing Costs of Hearing Loss Fit Testing In-Ear Dosimetry In-ear dosimetry measures/records worker’s actual noise dose, with and without protection Provides real-time monitoring and alerts when worker approaches/exceeds safe limits Only metric with direct potential to measure and prevent further progression of occupational hearing loss Reducing Costs of Hearing Loss Research > Alcoa Works Reducing Costs ofIntalco Hearing Loss Mean hearing threshold and 4 kHz)2000 – 2007 (N = 46) • Mean Hearing Threshold (2k, 3k, (2,3, 4kHz): Employees using continuous ESP starting in 2005 • Employees using continuous in-ear dosimetry starting in 2005 2000 - 2007 (N=46) 50 ESP Introduced Mean HTL 3,4,6kHz 45 trend line 40 35 30 25 20 15 10 5 0 2000 2001 2002 2003 2004 Year of test 2005 2006 2007 Reducing Costs of Hearing Loss Preventive Action After NIHL In practice, an OSHA-recordable STS is not a preventive action It is documentation of a hearing loss after the fact. How soon will an employee suffering NIHL be re-fit / re-trained ? “Best case scenario” per Hearing Conservation Amendment In-ear dosimetry “worst case” scenario … 1 Day • Retest • Audiometric test 0 2 4 6 8 10 Months 12 14 • Notification 16 In-ear dosimetry Reducing Costs of asHearing a Problem Loss Solver In-ear monitoring as a Problem Solver Employees with Documented Noise-Induced Hearing Loss or Standard Threshold Shift [STS] Employees At-Risk for NIHL Employee Training + Sampling Dual-Protection/Extreme Noise Exposure Engineering Controls Reducing Costs of Hearing Loss Real-Ear Attenuation at Threshold Loudness Balance (R.E.A.T.) (Real-Ear Attenuation Above Threshold) Microphone in Real-Ear In-Ear Dosimetry (M.I.R.E.) Ear plug fit-testing methods Audiometric FitCheck EARfit VeriPRO REAT REAT MIRE REAAT Sound booth Very Quiet Room Quiet Room Anywhere PAR PAR Derived PAR PAR Any earplug Selected modified earplugs Any earplug Any earplug Special training Special training Special training required required required Anyone can perform Reducing Costs of Hearing Loss OSHA Alliance: Best Practice Bulletin www.hearingconservation.org Additional Information www.howardleight.com Fit-Testing as a Training Tool Pre and Post-Test “How well can users predict their attenuation after a short fit-testing training session?" Fit-Testing as a Training Tool Pre and Post-Test Ability to Predict Noise Reduction (Each subject estimated atten. for each ear) Number of Ears 20 18 56% 16 14 12 10 32% 8 6 4 12% 2 0 Within 5 dB category +/- 7.5 dB +/- 12.5 dB (one Category off) (2 categories off) Reducing Costs of Hearing Loss Variation from Published NRR 10 Published NRR 0 -5 -10 -15 -20 Distribution of PARs -25 12 -30 0 10 20 30 40 50 10 60 Workers Workers Difference in dB 5 70 80 90 100 8 6 4 2 0 -30 -25 -20 -15 -10 -5 0 5 10 Variation from Published NRR 15 20 25 30 Reducing Costs of Hearing Loss Personal Factors Gender Age Distribution of PARs 12 Years in Noise Workers 10 Ear Canal Size 8 6 Familiarity 4 Model of Earplug 2 0 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 Program Factors Variation from Published NRR # Group Trainings # Personal Trainings REDUCING Reducing Costs COSTS of Hearing / CLAIMSLoss Difference on 2nd / 3rd Test 10 Variation from NRR 5 Published NRR 0 -5 -10 -15 -20 -25 -30 Subjects Trying a second earplug often improves attenuation Reducing Costs of Hearing Loss Earplug fit-testing as a Problem Solver • Training tool for noise-exposed workers • Train-the-trainer tool • Follow-up on significant threshold shifts in hearing • Documentation of HPD adequacy • Assessment of overall HCP effectiveness • Match HPD to worker’s specific noise level • Selection of appropriate HPDs for new hires • Benefits per Best Practices Bulletin (OSHA Alliance) Reducing Costs of Hearing Loss Tools for HCP Prevention Metrics PROS • Estimate CONS Measure • Cost • NRR obsolete • Time Investment • Fulfills OSHA compliance • Not standardized • Eliminates need for de-ratings • Medico-legal cases • Delineates non-occupational • Eliminates double protection • Provides employee feedback • (HPD Inventory control) Training + Motivation Training + Motivation Common Objections to Wearing HPDs “I already lost some of my hearing, “Won’t I get an ear so why should I wear them?” infection?” “Hearing protectors “I don’t need them! are uncomfortable I am used to the to wear.” noise.” “I can’t hear my co-workers if I wear them.” “Can I hurt my eardrums if I insert an earplug to deeply.” “I can always get fit with a hearing aid.” “My machine sounds different.” Training + Motivation Personalize Hearing Loss Show, Don’t Tell • Provide copy of annual audiogram to worker • Use personal examples to demonstrate consequences of hearing loss • Ask questions: • What is your favorite sound? • What sound would you miss the most if you couldn’t hear? • What sounds connect you to people and your environment? Training + Motivation Demonstrate Future Risk Training Materials • www.hearforever.org • www.hearingconservation.org • atl.grc.nasa.gov/HearingConserv ation/Resources/index.html • www.cdc.gov/niosh/topics/noise • www.dangerousdecibels.org www.hearforever.org/ILCA2010 Training + Motivation Send Clear Message On + Off Job HC Part of Everyday Life • Include recreational hearing conservation in annual training • Provide extra HPDs for home use • Promote Hearing Conservation at company/family events Training + Motivation Remove Barriers to HPD Use Make HPDs Available • Highlight “where to find HPDs” in annual training • Make sure HPDs are wellstocked and accessible • Include group of workers in selection process for increased acceptance • Offer wide variety to match comfort, job requirements Listen Up! Hear Forever Make Hearing Conservation a Part of Your Everyday Life HearForever.org